The present invention relates to a method for preconditioning lumps of sugar obtained from humidified and agglomerated caster sugar, before these lumps are dried.
For manufacturing agglomerated sugar in lumps, loaves or the like, a moulding machine is generally used which delivers at its outlet sugar lumps having the desired dimensions and these lumps are transmitted, by a suitable conveyor, to the entrance of an oven in which the lumps of sugar continue to be displaced, with a view to their progressive drying. Up to the present, the installations for moulding caster sugar and for drying the moulded lumps comprise a moulder proper where the caster sugar is agglomerated into lumps having the desired dimensions. On leaving the moulder, these lumps of moulded sugar are taken, by a conveyor, to the entrance of a drying oven in which prevails an atmosphere at relatively high temperature and rate of humidity (for example dry temperature from 70.degree. to 80.degree. C. and rate of humidity of up to 72%).
These installations present the drawback that the moulder sugar lumps which leave the moulder in the open air and at a relatively low temperature, undergo a fairly considerable thermal shock when entering the oven, and moreover, a condensation of steam may be produced on these relatively cold lumps (temperature lower than the dew point), which condensation is prejudicial to the subsequent drying operation.
Certain known installations comprise, to remedy this drawback, a chamber insulating the moulder and the outgoing conveyor from the ambient atmosphere. In this chamber, the temperature and humidity are maintained high, close to the temperature and humidity at the entrance of the oven, to avoid thermal shocks and condensations.
However, these installations present numerous drawbacks concerning accessibility to the moulder parts, lubrification and corrosion thereof maintenance, etc.
It is an object of the present invention to remedy these drawbacks by providing a method enabling a moulder to be used in the open air, whilst avoiding thermal shocks on the moulded sugar lumps.
A method of manufacturing lumps of compressed sugar is also known, which uses, for drying of the lumps, infra-red ray heating creating at the exit of the moulder a rise in temperature of the lumps of up to about 93.degree.-100.degree. C. in about 1 to 4 minutes, then a gradual reduction of the temperature between 66.degree. and 82.degree. C., still by means of infra-red heating ramps, with a view to drying the lumps by reducing their water content to less than 1%. In this process, the infra-red heating is used for drying the lumps.